Chapter 8 Numerical settings

The values of the following options, modifying the numerical program settings, can be changed by means of #define statements in the model-specific file as illustrated in the code blocks 2.3.1.2 and 3.3.1.2 for models implemented in R and in code blocks 2.3.2.1 and 3.3.2.1 for models implemented in C.

Setting name Default value Interpretation
MIN_SURVIVAL \(10^{-9}\) Minimum survival probability at which an individual is considered dead
MAX_AGE \(10^{6}\) Absolute maximum age after which an individual is considered dead
DYTOL \(10^{-7}\) Variable tolerance. The Newton iteration has converged when the norm of the right-hand side of the equations is less than RHSTOL and the norm of the consecutive adjustments to the solution vector of unknowns is less than DYTOL
RHSTOL \(10^{-8}\) Right-hand side tolerance. The Newton iteration has converged when the norm of the right-hand side of the equations is less than RHSTOL and the norm of the consecutive adjustments to the solution vector of unknowns is less than DYTOL
ALLOWNEGATIVE \(0\) If equal to 1 negative solution values are permissible, otherwise the program stops when a component of the solution vector becomes negative
FULLSTATEOUTPUT \(2\) If equal to 0 no output of the complete population state is produced. If equal to 1, output of the population state is produced in a binary file with .csb extension, with individuals originating from different states-at-birth weighted according to the stable distribution of produced offspring over states-at-birth and lumped into cohorts. If equal to 2, output of the population state is produced and individuals originating from different states-at-birth are stored as separate subpopulations.
COHORT_NR \(100\) Sets the number of cohorts in the output of the population state
ODESOLVE_INIT_STEP \(0.1\) Initial step size in the numerical integration of the ODEs. Initializes the globally accessible variable Odesolve_Init_Step.
ODESOLVE_MIN_STEP \(10^{-8}\) Smallest possible step size in the numerical integration of the ODEs. Initializes the globally accessible variable Odesolve_Min_Step.
ODESOLVE_MAX_STEP \(10.0\) Largest possible step size in the numerical integration of the ODEs. Initializes the globally accessible variable Odesolve_Max_Step.
ODESOLVE_FIXED_STEP - If defined, determines a value \(\Delta t\), which forces the ODE integration method to include all time values \(t=n\Delta t\) with \(n=0,1,\ldots\) among its integration time steps in addition to possibly intervening time values enforced by the adaptive step size mechanism. Initializes the globally accessible variable Odesolve_Fixed_Step.
ODESOLVE_ABS_ERR \(10^{-10}\) Absolute error in the numerical integration of the ODEs. Initializes the globally accessible variable Odesolve_Abs_Err.
ODESOLVE_REL_ERR \(10^{-8}\) Relative error in the numerical integration of the ODEs. Initializes the globally accessible variable Odesolve_Rel_Err.
ODESOLVE_FUNC_TOL \(10^{-8}\) Threshold value determining whether a stopping event in the numerical integration routine has been detected. Initializes the globally accessible variable Odesolve_Func_Tol.
JACOBIAN_MIN_STEP \(10^{-7}\) Absolute minimum change in variable when computing Jacobian matrix. Initializes the globally accessible variable Jacobian_Min_Step.
JACOBIAN_STEP \(10^{-4}\) Relative change in variable when computing Jacobian matrix. Initializes the globally accessible variable Jacobian_Step.
JACOBIAN_UPDATES \(5\) Number of Newton adjustments before the Jacobian matrix is computed anew. Initializes the globally accessible variable Jacobian_Updates.
EBTMETHOD \(1\) Type of EBT method to use for simulating ecological dynamics. Possible values are 0 for using the simplified EBT method proposed by Brännström, Carlsson and Simpson (2013) or 1 to use the original EBT method (de Roos (1988)).